the act of sexual intercourse in such a vile, filthy manner that it is happily reminiscent of the ugly, disgusting way in which dogs have sex.
Ned: Hey dude, get any pussy?
Ed: Oh dude, I was dog fucking that skank so bad the film would probably be illegal if sold in the civilized world. I just dog fucked that nasty cunt.
to be at work but not actually doing any work, at all. Another way of saying you/someone is lazy.
Tim: man, I havn't done a thing all day
Jim: you are such a dog fucker
Jim: Damit Tim will you do somthing, quit dog fucking
Tim: Im so tired and half cut, Im gona dog fuck all day